Audemars Piguet Perpetual Calendar Openworked

Audemars Piguet's Royal Oak Perpetual Calendar Openworked, reference 26585CE.OO.1225CE.01, comes in black ceramic and measures 41 mm across. The case stands 9.9 mm thick, a slim figure given the complication housed inside. A sapphire crystal covers the skeletonized dial, which lays bare the movement's architecture and its pink gold components. Calibre 5135, a self-winding perpetual calendar movement, drives the watch and tracks date, weekday, month and moon phase without adjustment through the leap year cycle. The perpetual calendar sits alongside the moon phase display as the two functions that define this piece. A black ceramic bracelet closes with a folding clasp made of titanium. Water resistance is modest at 20 metres, a reminder that this is a dress watch built for precision rather than the depths.